Hiroshima's 'Shockwave,' 60 Years LaterSixty years ago Saturday, the B-29 bomber Enola Gay loosed a 10,000-pound atomic bomb over the Japanese city of Hiroshima. We remember Aug. 6, 1945, and the people whose lives were changed by it.

In a new book, Shockwave: Countdown to Hiroshima, BBC producer Stephen Walker focuses on the three weeks that lead up to the attack and on the stories of individuals, policymakers, diplomats, physicists, soldiers, airmen and residents of Hiroshima.

We talk to Walker, as well as two men who were aboard the Enola Gay on Aug. 6, 1945, about that fateful day.

Guests:

Stephen Walker, author of Shockwave; BBC producer

"Dutch" Van Kirk, navigator of the Enola Gay

Morris Jepson, weapons test officer on the Enola Gay

Excerpt from Shockwave

Chapter One

Sunday, July 15, 9 P.M.Trinity Test Site,Forty Miles South of Socorro, New Mexico

Don Hornig stared up at the tower. The wind and rain whipped through the steel latticework. The storm that had been building throughout the day had finally erupted in all its fury. Flashes of lightning lit the San Andres mountains to the south, and the desert echoed with the growl of thunder. The tower loomed 103 feet above Hornig's head, a network of black braces and girders reaching upward like a giant electric pylon. By now the clouds were racing so low across the sky, he could barely see the top. Which was just as well, really. He did not want to think about what was at the top.

He began to climb. The wet steel slipped between his fingers and the rain stung his eyes, making it difficult to see. He wore no safety harness. Rung by rung, he pulled himself up the ladder. It was slow going, but he was only twenty-four, and the long Sunday rides over the Pajarito mountain trails near Los Alamos kept him fit. Once or twice he stopped, and he could see the guards below him looking up, like ants on the desert floor. They seemed a long way down.

At the top of the tower, a simple corrugated tin shack rested on a square wooden platform. It was a flimsy, cheaply made structure, obviously not designed to last. It was not much bigger than a garden shed. One of its walls was open to the elements. Hornig stepped off the ladder beside it, pausing by the entrance. A huge, dimly discernible shape crouched inside. There was a bare sixty-watt bulb hanging from the roof. Hornig switched it on and peered inside.

Hulking on a cradle was a metallic-gray, bloated, four-ton steel drum, and it took up almost every inch of space in the shack. Even by day it would have looked ominous, but it looked especially so now with the wind whipping the tin walls, and the dim bulb swaying from the ceiling, and the lightning and thunder edging nearer. A fantastic complex of cables sprouted from its sides like a spillage of guts or arteries, as if it were somehow not inert at all but actually organic, a growing, living, autonomous embryo, awaiting the moment of its birth. Perhaps in acknowledgment of its essence, its creators had even given it a name. A number of names, in fact. They called it The Beast, The Gadget, The Thing, The Device. Sometimes they just called it It. The one thing nobody ever called it was what it actually was. The world's first atomic bomb.

Hornig squeezed down beside it. The rain pelted on the tin roof like a thousand hammer blows. The wind rattled the thin walls of the bomb's cage. In a few hours, a fellow scientist named Joe Mc-Kibben, standing in a concrete bunker exactly 10,000 yards to the south of this tower, would initiate the final act in what was almost certainly the biggest and most expensive scientific experiment in history. McKibben would press a switch on a panel that in turn would close an automatic timing circuit and begin a forty-five-second countdown. At the end of that time a number of different things could happen. The bomb could fail to go off. Or it could detonate with varying magnitudes of explosion. Or, as one Nobel Prize-winning scientist believed possible, it could set fire to the earth's atmosphere, in the process destroying all life on the planet. The difficulty was that nobody knew.

The only other object in the tin shack, besides an atomic bomb, was a telephone. It was Hornig's sole means of communication with the outside world. The lines ran down the tower and out through the desert to the control bunker. They were supposed to call him when it was time to come down, and he was supposed to call them if anything went wrong. That was the theory, at any rate. In practice, if anything did go wrong, there might not be much time to start making phone calls.

He had not asked for this job. It was a last-minute decision, made only a couple of hours earlier by the director of the bomb's laboratory, J. Robert Oppenheimer. Oppenheimer was worried about pretty much everything that night, but right then one of his main concerns was security. He wanted somebody to go up there, babysit the bomb, keep a watchful eye on things. Maybe Hornig was unlucky enough to be in the wrong place at the wrong time, but he was an obvious choice. A brilliant Harvard-trained chemist, he had spent the early war years in New England researching underwater explosives. One day in 1943 his boss had called him into the office and told him he was wanted for a job so secret, not even his boss had a clue what it was. Within days, Hornig had sold his beautiful forty-five-foot yacht Siesta, bought himself a secondhand 1937 Ford Coupe, and together with his twenty-year-old wife, Lilli, an equally brilliant German Jewish refugee whom he had met in a chemistry course at Harvard, headed out west. Their destination was a place he had never heard of. It was called Los Alamos, a secret laboratory in the high mesas northwest of Santa Fe, where they were building very special bombs.

Over the next two years, Hornig designed a wondrously complex piece of equipment called the X-unit. Essentially the bomb's electric trigger, it would, at the requisite time, send a five-and-a-half- thousand-volt charge to sixty-four detonators arranged in geometric patterns around the bomb's sphere, like cloves stuck in an apple. Of course, if anything went wrong with the X-unit, there would be no firing charge, no detonation, no explosion ...